This device is currently in use. Close any programs or windows that might be using the device, and then try again.

Assuming that you’ve closed all the programs that could be using the device, you have a few options here.

Firstly, you can try to work out which program is using the device and close it using a Microsoft program called Process Explorer. To do this, download Process Explorer, then run it as administrator (right click -> Run as administrator). Click File -> Show Details for All Processes. Click Find -> Find handle or DLL. Type the letter of the mass storage device that is reportedly currently in use (ie: D:), then click Search. The results will show you the processes that are currently using the device. You can close them from this interface.

In my case, some system resource programs were using the device, so I couldn’t close them without killing Windows. This was because the drive was shared and set to allow indexing. to fix this, disable the share and indexing on the drive.

Failing this, you can turn off write caching so you don’t need to disconnect the USB device. To do this, go to Printers and Devices in the Control Panel, right click the USB mass storage device and go to the properties. Click the Hardware tab, then Properties. On the General tab, click Change settings. On the Policies tab check the option for Quick removal and click OK.